1. Field of the Invention
This invention generally relates to a linear motion device and a lens drive device. The linear motion device can be used as, for example, an optical-pickup drive device. This invention particularly relates to a linear motion device and a lens drive device each including a mechanism for converting a rotational motion to a linear motion.
2. Description of the Related Art
Japanese patent application publication number 09-033782/1997 discloses a lens moving device including a feed screw, a barrel, a connector, and a lens frame. The barrel has a threaded hole through which the feed screw extends. The thread of the barrel meshes with the feed screw. As the feed screw rotates, the barrel moves linearly along the axis of the feed screw while being inhibited from rotating. The lens frame retains a lens. The lens frame is slidably supported by a pair of guide shafts extending parallel to the optical axis of the lens. The connector couples the barrel and the lens frame so that the lens frame and the lens will linearly move along the optical axis of the lens in accordance with the linear movement of the barrel. The connector includes a leaf spring member having a base end fixed to the barrel and a distal end formed with a projection. The lens frame has a recess into which the projection of the leaf spring member fits. Thereby, the leaf spring member engages with the lens frame.
In the lens moving device of Japanese patent application 09-033782/1997, a radial-direction play (backlash) between the lens frame and each guide shaft and another inter-parts play about each guide shaft lower the accuracy of the linear movement of the lens frame, that is, the accuracy of control of the axial-direction position of the lens. Accordingly, it is desirable to reduce or eliminate such a radial-direction play and an inter-parts play.
In the lens moving device of Japanese patent application 09-033782/1997, there is an inter-parts play concerning the lens frame which tends to cause axial-direction positional errors of the lens frame and the lens. Accordingly, it is desirable to reduce or eliminate such an inter-parts play.